/**
 * Copyright (c) 2016-2020 https://github.com/zhaohuatai
 *
 * contact 824069438@qq.com
 *  
 */
package org.zfes.snowy.core.util.encypt;

import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.Cipher;

import org.zfes.snowy.core.exceptions.AppRuntimeException;

public class RSAUtil {
	 /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";
    
    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";
    
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;
    
    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;
    
    public static void main(String[] args) {
    	  Map<String, Object> keyMap = RSAUtil.genKeyPair();
  	    String publicKey = RSAUtil.getPublicKey(keyMap);
  	    String privateKey = RSAUtil.getPrivateKey(keyMap);
  	    System.out.println(publicKey);
  	  System.out.println(privateKey);
	}

    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     * 
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() {
        KeyPairGenerator keyPairGen;
		try {
			
			keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
			
	        keyPairGen.initialize(1024);
	        KeyPair keyPair = keyPairGen.generateKeyPair();
			
	        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
	        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
	        Map<String, Object> keyMap = new HashMap<String, Object>(2);
	        keyMap.put(PUBLIC_KEY, publicKey);
	        keyMap.put(PRIVATE_KEY, privateKey);
	        return keyMap;
        
		} catch (NoSuchAlgorithmException e) {
			throw new AppRuntimeException(e.getMessage());
		}
    }
    
    /**
     * <p>
     * 获取私钥
     * </p>
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }
    public static Key getPrivateKeyObj(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return key;
    }
    
    /**
     * <p>
     * 获取公钥
     * </p>
     * 
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }
    public static Key getPublicKeyObj(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return key;
    }
    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * 
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) {
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
		try {
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
			PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
		    Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
	        signature.initSign(privateK);
			signature.update(data);
	        return Base64.getEncoder().encodeToString(signature.sign());
		 } catch (Exception ea) {
			 throw new AppRuntimeException(ea.getCause());
		}
    
    }
    /**
     * <p>
     * 校验数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     * 
     * @return
     * @throws Exception
     * 
     */
    public static boolean verify(byte[] data, String publicKey, String sign) {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		try {
			KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		    PublicKey publicK = keyFactory.generatePublic(keySpec);
		    Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		    signature.initVerify(publicK);
		    signature.update(data);
		    return signature.verify(Base64.getDecoder().decode(sign));
		} catch (Exception e) {
			 throw new AppRuntimeException( e.getMessage());
		}
   
    }
    /**
     * <p>
     * 私钥加密
     * </p>
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey){
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        try {
        	  KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
              Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
              Cipher   cipher = Cipher.getInstance(keyFactory.getAlgorithm());
              cipher.init(Cipher.ENCRYPT_MODE, privateK);
	        int inputLen = data.length;
	        ByteArrayOutputStream out = new ByteArrayOutputStream();
	        int offSet = 0;
	        byte[] cache;
	        int i = 0;
	        // 对数据分段加密
	        while (inputLen - offSet > 0) {
	            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
	                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
	            } else {
	                cache = cipher.doFinal(data, offSet, inputLen - offSet);
	            }
	            out.write(cache, 0, cache.length);
	            i++;
	            offSet = i * MAX_ENCRYPT_BLOCK;
	        }
	        byte[] encryptedData = out.toByteArray();
	        out.close();
	        return encryptedData;
        } catch (Exception e) {
			throw new AppRuntimeException( e.getMessage());
		}
    }
    
    /**
     * <P>
     * 私钥解密
     * </p>
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey){
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        try {
	        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
	        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
	        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
	        cipher.init(Cipher.DECRYPT_MODE, privateK);
	        int inputLen = encryptedData.length;
	        ByteArrayOutputStream out = new ByteArrayOutputStream();
	        int offSet = 0;
	        byte[] cache;
	        int i = 0;
	        // 对数据分段解密
	        while (inputLen - offSet > 0) {
	            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
	                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
	            } else {
	                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
	            }
	            out.write(cache, 0, cache.length);
	            i++;
	            offSet = i * MAX_DECRYPT_BLOCK;
	        }
	        byte[] decryptedData = out.toByteArray();
	        out.close();
	        return decryptedData;
        } catch (Exception e) {
			throw new AppRuntimeException( e.getMessage());
		}
    }
    /**
     * <p>
     * 公钥解密
     * </p>
     * 
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        try {
	        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
	        Key publicK = keyFactory.generatePublic(x509KeySpec);
	        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
	        cipher.init(Cipher.DECRYPT_MODE, publicK);
	        int inputLen = encryptedData.length;
	        ByteArrayOutputStream out = new ByteArrayOutputStream();
	        int offSet = 0;
	        byte[] cache;
	        int i = 0;
	        // 对数据分段解密
	        while (inputLen - offSet > 0) {
	            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
	                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
	            } else {
	                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
	            }
	            out.write(cache, 0, cache.length);
	            i++;
	            offSet = i * MAX_DECRYPT_BLOCK;
	        }
	        byte[] decryptedData = out.toByteArray();
	        out.close();
	        return decryptedData;
        } catch (Exception e) {
			throw new AppRuntimeException( e.getMessage());
		}
    }
    /**
     * <p>
     * 公钥加密
     * </p>
     * 
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey){
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        try {
	        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
	        Key publicK = keyFactory.generatePublic(x509KeySpec);
	        // 对数据加密
	        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
	        cipher.init(Cipher.ENCRYPT_MODE, publicK);
	        int inputLen = data.length;
	        ByteArrayOutputStream out = new ByteArrayOutputStream();
	        int offSet = 0;
	        byte[] cache;
	        int i = 0;
	        // 对数据分段加密
	        while (inputLen - offSet > 0) {
	            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
	                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
	            } else {
	                cache = cipher.doFinal(data, offSet, inputLen - offSet);
	            }
	            out.write(cache, 0, cache.length);
	            i++;
	            offSet = i * MAX_ENCRYPT_BLOCK;
	        }
	        byte[] encryptedData = out.toByteArray();
	        out.close();
	        return encryptedData;
        } catch (Exception e) {
			throw new AppRuntimeException( e.getMessage());
		}
    }
    
}
